Lens-grinding lap



HV'VENTOR.

E. G. ROBINSON LENS'GRINDING LAP Filed Jam. 15

March 18, 1924..

ATTORNEY.

Patented Mar. 18, 1924..

ERDIS G. ROBINSON, OF COL'UMBU S, OHIO LENS-GRINDING- LAP.

Application filed. January 15, 1920. Serial Iva- 351,545.

' To all whom it may concern.

Be it known that I, ERDIS Gr. Ronmson, a citizen of the United States of America,

residing at Columbus, in the county of Franklin and State of Ohio, have invented certain new and useful Improvements in Lens-Grinding Laps, of which the following is a specification.

My invention relates to lens grinding laps and it aims to provide a novel structure of laps which will facilitate the replacement of the grinding surfaces without in any way detracting from the stability and comparative rigidity of these surfaces. Hitherto, 'grinding laps have ordinarily taken the form of single piece elements which must, of necessity, be of relatively hard metal in order that they may withstand the wear to which they are subjected by the rotating element upon which they are mounted. The difficulty with this is that, though the relatively hard metals are required inorder to resist the wear upon the sockets of the laps, et cetera, the surfaces which they offer are not the most desirable for grinding purposes. They are too hard to present the most effectual retaining surface for granular or powdered abrasive material,

I have recognized the undesirability of thi compromise and I have provided a base element of relatively hard material and of material sufliciently hard to withstand the wear to which it will be subjected. Then, in conjunction with this, I have provided removable lens-grinding elements which are of relatively soft material and, in fact, of that degree of softness best suited to the retention of the abrasive material. My lensgrinding elements are preferably die-cast or they may be machined like the ordinary lap or cast true to curve. At any rate, they are of a relatively light and cheap material which may be utilized as scrap and re-cast but which are nevertheless amply rigid and supported with ample rigidity during the grinding operation which they perform,

The preferred embodiment of my invention is shown in the accompanying drawings wherein similar characters of refer ence designate corresponding parts Figure 1 is a side elevation, partially in section, of my lens-grinding lap with the two parts assembled and shown in operative relation to a lens.

Figure 2 is a detail View of the lens-grinding surface element of my lap.

Figure 3 is a detail view of the body portion of my lens-grinding lap.

In the drawings, the body portion of my lens-grinding lap is shown in Figures 1 and S and it comprises a shank 1 having atapered socket 2 therein and having a large head 3 of disk-like form. This head 3 is. provided with a socket 4 extending downwardly into the disk-like member at some point off center and a concentric socket 5.

My-lens-grinding surface element is shown best in Figure 2 and it comprises a main tapered stud member-.5 concentrically ,de-

pending froma head 7 which is of circular form and which is adapted to fitupon the disk-like member 3. Thehead member 7 is also provided with a downwardly depending lug 8 which is so positioned that it will fit into the'socket 4:.

I11 operation, the 1ens-grinding surface element is placed in position upon the body portion with its stud 6 extending downward- 1 1y into the socket 5 and with its lug 8 extending downwardly into the socket 4. In this position, the lens-grinding element is firmly supported upon its body portion'in such a way that it is amply rigid and is prevented from turning with relation to such body portion by the lug 8 extending into the socket 4t.

It will be obvious from this that I have provided a lens-grinding lap wherein the actual lens-grinding surface may be cast of any alloy and of one best suited to the retention of the granular or abrasive ma terial. Thus, the ideal material may be selected without the necessity for compromising in order to obtain the rigidity which is necessary when the lap is made in one piece. Because the lens-grinding element is removable from its body portion and is of relatively light material and bulk, it will be possible to greatly lighten the bulk of the laps in stock since a large number of lap surfaces may be used in connection with a single body portion. Obviously, there will be a great reduction in the cost and a great reduction in the scrap bulk to be discarded, together with the additional advantage that this material may again be used by recasting.

It will be seen that I have provided a structure wherein it is possible to select the grinding surface solely on account of its suitability for grinding and with-out regard to the requirements regarding Wear that must necessarily be considered in a one-piece lap. The result is that I am able to greatly increase the efiiciency of lens grinding laps, it being recognized that soft metal will retain the abrasive material better, will grind more rapidly and will last longer.

Having thus described my invention, what I claim is:

1. A lens grinding lap comprising a body portion, a removable 'rinding surface element, a centering stud on the base of said element, and an intermediate stud on the base of said element, said body portion having sockets for said studs.

2. A lens grinding lap comprising a rotatable body member and a grinding mern her, the body nember having a socket therein concentric with the axis of rotation thereof; a lug on said grindin member concentric with the axis of rotation thereof and adapted to fit into said socket, the body member hav ing a socket therein eccentric to the axis of rotation thereof, a lug onsaid grinding member eccentric to the axis of rotation thereof and adapted to fit into said second-mentioned socket, said parts being adapted to be assembled and disassembled by the mere longitudinal relative movement thereof.

A lens grinding lap con'iprisinga body member and a grinding member, said parts having lugs thereon and sockets therein registe-ring with each other to prevent relative lateral or relative rotative movement of said parts, said parts being adapted to be assembled and disassembled by a mere longitudinal relative movement thereof, and a shank on said body portion having a tapered socket therein.

4. A lens grinding lap comprising a body member and a grinding member, the body member having a socket therein concentric with the axis of rotation thereof, a lug on said grinding member concentric with the axis of rotation thereof and tapered to fit into said socket, the body member having a socket therein eccentric to the axis of rotation thereof, a lug on said grinding member' eccentric to the axis of rotation thereof and adapted to fit into said second mentioned socket, said parts being adapted to be assembled and disasse bled by a-niere longitudinal relative movement there of, and a shank on said body portion having a tapered socket therein.

5. A rotatable lens grinding lap com 'nrising a body member and-a grindin member, the body'member having a socket therein concentric with the axis of rotation thereof, a lug on said grinding member concentric with the axis of rotation thereof and adapted to fit into said soc rat, the body member having a socket therein eccentric to the axis of rotation thereof, a leg on said grinding member eccentric to the axis of rotation thereof and adapted to fit into said second-mentioned socket, said parts being adapted to be assembled and disassembled by a mere longitudinal relative movement thereof, and a shank onsaid body portion having a tapered socket therein concentric with the axis of rotation. V

In testimony whereof I hereby my signature.

ERDIS G. ROBINSON. 

